Multibranched Gold–Mesoporous Silica Nanoparticles Coated with a Molecularly Imprinted Polymer for Label-Free Antibiotic Surface-Enhanced Raman Scattering Analysis

Abstract

We describe the preparation of multibranched gold−silica−molecularly imprinted polymer (bAu@mSiO 2 @ MIP) core−shell nanoparticles, with their specific ability to recognize enrofloxacin (ENRO), and their application as labelfree nanosensors for the specific detection of the antimicrobial by surface-enhanced Raman scattering. The use of these nanocomposites results in a large enhancement of the Raman scattering of ENRO upon binding of an antibiotic to the selective recognition sites in the MIP. These are in the proximity of the gold core branches that act as intrinsic hot spots providing highly localized and strongly enhanced electromagnetic fields caused by plasmon resonance. The effect of the multibranched morphology of the gold cores (bAu) on the optical spectroscopic response of the bAu@mSiO 2 @MIP nanosensors is investigated with the aim of improving ENRO detection. The optimized nanostructures allowed us to achieve a detection limit of 1.5 nM for ENRO, which is 2 orders of magnitude lower than those for previously reported Au@MIP nanosensors, additionally providing negligible cross-reactivity toward other potential interfering species.

Nanostructured Assemblies of Gold and Silver Nanoparticles for Plasmon Enhanced Spectroscopy Using Living Biotemplates

“…Raman spectroscopy is an analytical technique commonly used in biomedical applications. Over the years, a wide variety of molecular targets have been investigated by SERS using active nanoparticles, mainly gold and silver [2,3,11,12,[26][27][28][29][30][31][32][33][34]. The plasmonic origin of the phenomenon is fully understood [19,37], and nowadays the major effort focuses on the fabrication of new substrates for SERS [38].…”

“…Several techniques allow tuning the characteristics of surfaces for SERS, for instance through lithographic methods, precipitation from colloidal suspensions, or by the physical vapor deposition of metals on a nanostructured surface of silicon or ZnO [27]. Anisotropic metal nanoparticles, on the other hand, offer the possibility of creating "hotspots" of enhanced activity [26,[28][29][30][31][32][33].…”

Plant-derived silica nanoparticles and composites for biosensors, bioimaging, drug delivery and supercapacitors: a review

“…e Gold-mesoporous silica under plasmonic photothermal with irradiation for 14 h at 514 nm under 15 mW, reprinted with permission from Croissant and Guardado-Alvarez (2019). f Multibranched-polymer composite with goldsilica core-shell nanoparticles, reprinted with permission from Carrasco et al (2016). CTAB: cetyltrimethylammonium bromide enhances the properties of the core material (Chatterjee et al 2014).…”

Silica‐Coated Plasmonic Metal Nanoparticles in Action

“…For instance, an increase of up to two orders of magnitude compared to previous methods in the detection of enrofloxacin by SERS was achieved by coating spiked Au/mSiO2 particles with a molecularly imprinted polymer with specific affinity toward this antibiotic. [134] This molecule was therefore preferentially placed at the hot-spots and was consequently detected by SERS. Another common strategy to enhance the SERS signal, and thereby improve the sensitivity of molecular detection, is related to increasing the density and enhancement strength of the hot-spots.…”